Have you tried disconnecting one ignition wire or injector wire at a
time to see which one makes the least difference?
   Be sure there is no leak in your exhaust upstream of the O2 sensor.
Check carefully for vacuum leaks.  Try a bottle of injector cleaner.
   good luck,
Larry A.

Craig Oda wrote:
> Hi,
> I have a '83 1.9L watercooled that recently failed the hydrocarbon test
> for CA SMOG. CO levels passed.
> I just installed a new O2 sensor, but no change.
>
> Engine runs fine at highway speed, but there is a noticeable pulsing of
> the exhaust at idle, almost as if one of the cylinders was not fully
> combusting.
>
> Valves appear to be properly adjusted and cylinder compression appears
> to be within spec (lowest was I think around 120).  I can check again
> since I have the tool.
>
> Any ideas on what to look for?
>
> If I can't fix this, in the next few days, I'm going to bring it into a
> mechanic.  I'm thinking about Fred's Garage in Redwood City, CA.  Any
> recommendations?  I live/work in Palo Alto, CA, so there is Ole's Garage
> near my office, but I don't know if he is a VW man or not.
>
> I would love to take it to Ben's place in Sacramento, but it's a bit too
> far for me to drive there with my wife and drop off the van.
>
> But, hey, there is also the slim chance that i'll find the problem
> myself (with the help of the friendly people on this list).
>
> Peace and Thanks.
> -- Craig
>